World’s Soil Resources

4.3.3 | Land use change resulting in irreversible soil change
In this section we deal with soil sealing and mining, which have been identified as two important soil
degradation processes occurring around the world. The current extent and rate of growth of soil sealing and
mining are significant, and create considerable risks to essential ecosystem services. These changes in land
use nearly always require a trade-off between various social, economic and environmental needs.
Sealing and land take
The ongoing urbanization and conversion of the landscape with settlements, infrastructure and services is
occurring in many regions. Europe and Asia, in particular, are experiencing high rates of urban expansion and
urban sprawl, and there are often insufficient incentives to re-use brownfield sites. These factors are causing
an increase in land take and soil sealing. The drivers are essentially economic and demographic growth. In
Europe, America and Oceania, at least 70 to 80 percent of the population currently lives in urban areas. The
rate of urbanization is expected to continue to increase, particularly in Asia and Africa.
The concept of land take covers all forms of conversion for the purpose of settlement, including: the
development of scattered settlements in rural areas; the expansion of urban areas around an urban nucleus;
the conversion of land within an urban area (densification); and the expansion of transport infrastructure such
as roads, highways and railways. Broadly, this discussion considers as land take any conversion of agricultural,
natural or semi-natural land cover to an ‘artificial’ (e.g. human-made) area. Artificial land cover classes are
categorized in the Corine Land Cover system – see Table 4.3.
A greater or smaller part of land take will result in soil sealing. Soil sealing means the permanent covering
of an area of land and its soil by impermeable artificial material such as asphalt or concrete, for example
through buildings and roads. As shown in Figure 4.6, the sealed area is only part of a settlement area. Gardens,
urban parks, leisure areas and other green spaces within the boundaries of settlements are not covered by an
impervious surface or are only partially covered. They thus form part of a land take but do not contribute to
soil sealing (Prokop, Jobstmann and Schöbauer, 2011.) The ratio between sealed area and total area for a given
land use class is measured by the soil sealing index. An example of this index, calculated for the Italian region
of Emilia-Romagna, is shown in Table 4.4.
Table 4.3 Artificial areas in Corine Land Cover Legend
Status of the World’s Soil Resources | Main Report Soils and Humans
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